1. Field of Invention
The present invention is an electronic device used to activate a municipal mechanical fire siren upon the receipt of a signal of fire from any one of a plurality of inputs. Its placement would be in a fire station to alert firefighters when they have an alarm by sounding the fire siren.
2. Description of Prior Art
When volunteer fire departments in small towns across the country receive a call for help, the primary method used to call firefighters to the station is by the use of a large fire siren, usually mounted on or in close proximity to the firehouse. It is powerful enough to be heard all through the surrounding area, and the firefighters, upon hearing the siren, are expected to repair with all possible haste to the scene of the fire. If the siren is not activated when an alarm of fire has been reported to the fire station, then the firefighters are not immediately notified of the alarm, and response time is delayed, possibly causing unnecessary loss of life and property.
Most municipal fire sirens today are radio-activated; that is, a central command center receives all telephone calls for help and when one is received, they transmit radio tones of a specific frequency to the fire department needed to respond to the call. At the fire station called, there is a radio receiver that upon receipt of these specific tones, close a dry contact switch for a few seconds. A siren activation system in use at that firehouse can utilize this switch closure to start its process of turning on and turning off the fire siren to produce the wailing effect that is so familiar. After a predetermined length of time, the siren activator shuts down until the next alarm is received. In some cases, a fire department may have their fire siren sound for one cycle at noon each day, as a daily test.
In the past, the method used for turning the siren on and off upon receipt of an alarm was handled by a series of small 120 Volt AC motors. These motors would have cam plates attached to them that would turn with its corresponding motor. A microswitch riding on the edge of the cam would open and close with the contours of the cam. The current to the fire siren was controlled by the opening and closing of this microswitch via several step-up relays, as most siren motors operate around 220-440 Volts in 3-phase form. After a predetermined amount of cycles of the cam, another microswitch would usually shut down the entire system. If the department wanted their siren to cycle once at noon each day as a daily test of the siren, then a separate AC clock/timer had to be purchased to keep track of time. This clock/timer would be preset to trip a microswitch at noon each day and an entirely different series of cams and microswitches would be needed to sound the siren for one cycle at noon and shut down afterward. An example of this older type of mechanical timer is discussed in U.S. Pat. No. 3,728,707 (Herrnreiter).
There are many problems associated with the use of a system of AC motors, cams, and microswitches:
1. The entire system operates at a minimum voltage of 120 volts AC (excluding the siren motor itself). If there was to be an AC power failure, nothing short of an emergency generator would be able to keep the system operational. Without AC power, a reported alarm could go unnoticed by firefighters as the siren would not be operational.
2. By using AC motors, microswitches, cams, and the like, it is observed that there are many moving parts that can be subject to wear and tear, as well as frequent breakdown.
3. Any indicator lights used with the system also use AC voltage. These lamps tend to become very warm after awhile and in some cases, have been known to start a fire, thereby causing a fire in the fire station.
4. The noon clock, also dependent on AC power, will lose track of time during a power failure and may activate the noon test at any time during the day after AC power is restored, until it is manually reset by personnel. There are some timers on the market today that use a spring or a backup battery to keep track of time during a power failure, but their usefulness only spans over a few hours and only function to support the clock- nothing else.
5. If the department wanted to add additional features to their siren activation system (i.e. noon timer, heat detectors to monitor for fire in the station, etc.) they had to seek out additional components and add them to the existing system. This would more often than not result in several different circuit panels, fuse boxes, and additional wiring to be added to an already cluttered system.
6. AC powered components can be susceptible to power surges and interference by lightning and electrical storms. These can quite often lead to false activation of AC powered siren activation systems.
Today, most fire departments in the country have assigned radio receivers or pagers to their personnel. This affords them the opportunity to page firefighters when there is an alarm in addition to activating the siren. The radio page consists of a voice announcement made by a dispatcher actually describing the type of alarm and its location. In most instances, this dispatcher is the person that answers the phone when there is a call for assistance. Approximately 97% of all fire calls to most small fire departments are received from the public via telephone and processed through a dispatcher. The remaining 3% of alarms reported occur usually under one or more of the following methods: 1.) The fire department may employ the use of heat detectors in the building. These are connected to the siren activation system either directly or through a commercially available fire alarm system installed to protect the premises only. If a fire is detected within the building, this would automatically activate the fire siren, thus alerting fire personnel. 2.) A manual pull station (fire call box) is attached to the outside of the building so that passers-by may turn in an alarm to the fire department directly, if necessary. This pull station is also directly connected to the siren activation system. 3.) In some cases, a department may monitor a remote location within its fire protection district for fire. Some examples of remote locations may include a school, church, or government office. Should a fire be detected at any of these locations, a signal can be transmitted to the fire station (usually over a telephone cable or some similar method) to automatically activate the fire siren. In the example of remote location monitoring, there needs to be some sort of fire alarm system in operation at the location to be monitored. There are many examples of fire detection and warning systems in the prior art, specific examples include U.S. Pat. Nos. 4,086,573 (Sasaki); 4,092,642 (Green et al); 4,357,602 (Lemelson); 4,491,830 (Miyabe); 4,550,311 (Galloway et al); 4,673,920 (Ferguson et al). In each of these examples, the systems being described are responsible for monitoring for an outbreak of fire. Upon detecting such a situation, it will then alert occupants of the building, provide emergency assistance in the form of visual and audio alerts, sprinkler activation and the like, and provide means to notify emergency personnel. The siren activation system being discussed in this application would actually receive the signal for assistance from the fire alarm systems described in the prior art. In essence, the siren activation system would provide a second level of notification of fire, but would in actuality be the first level of notification to fire personnel.
If an alarm of fire is reported to the fire department using any of the three methods listed above, the siren is activated without the intervention of a dispatcher. Since the dispatcher (who could technically be located many miles away from the fire station) did not activate the alarm for the department, he is unaware that there is an alarm in progress and therefore does not page firefighters as to the location of the fire. The firefighters upon hearing the siren, would have to "figure out" where the fire is once they reach the station. With the older AC mechanical siren activation systems described earlier, should the siren fail to operate for an automatically activated alarm, then no one would know that there was a fire or similar emergency in progress.